Preheat oven to 400 degrees. Place a large pot of water over high heat and cover. Place a large saute pan with 2 tbsp oil or lard over medium heat. Once the oil is hot, add the mushrooms to the pan and saute for 7-10 minutes or until the mushrooms are fully cooked and slightly caramelized. Toss or stir occasionally. Season with a pinch of kosher salt and black pepper then deglaze the pan with sherry vinegar. Allow all of the vinegar to cook out, then remove the mushrooms from the pan and set aside.
Begin the cheese sauce. Add 4 tbsp butter to a medium-sized sauce pan and place the pan on the stove over medium heat. Once all the butter is melted and hot, whisk in 4 tbsp flour. Cook the flour, whisking, for about 30 seconds , just long enough to get rid of the raw flour taste, but not long enough for the flour to start caramelizing. Add the thyme, rosemary, sage, and red pepper flakes. Continue stirring and allow the herbs to saute for about another 30 seconds. Slowly pour in the milk while whisking continuously, so the roux and milk incorporate smoothly and there are no lumps. Allow the bechamel to come to a simmer (it won't gain it's full thickness until it does), stirring occassionally.
Pasta: Liberally salt the pot of boiling water, almost to the point it tastes like sea water. This may take a few handfuls of salt . Add the pasta to the water and cook the pasta for a minute or two less than the suggested time on the box.
Once the bechamel has reached a simmer, stir in the chevre, cheddar, 2oz of parmigiano, and truffle oil until all the cheese has melted. Turn off the heat and and taste the sauce for seasoning levels. Season with salt and pepper as necessary. In small mixing bowl, mix together the panko and remaining 2oz of parmigiano reggiano.
Strain the pasta immediately once finished cooking. In a mixing bowl, toss the pasta, cheese sauce, and mushrooms together. Pour the macaroni and cheese into a deep glass or ceramic loaf pan and sprinkle the panko/parmigiano mixture evenly across the top.
Bake the mac-n-cheese in the upper part of the oven for about 15 to 20 minutes or until the topping is golden and the cheese sauce is bubbly. Serve immediately.